1. Technical Field
The present invention relates to a form-fill-seal machine for continuously manufacturing bags, and in particular to a form-fill-seal machine provided with a gusset-forming mechanism for forming a gusset (i.e., an inwardly folded portion) on both side parts of the bag.
2. Related Art
Form-fill-seal machines are in widespread use as bag manufacturing and packaging devices for simultaneously manufacturing bags and filling them with packaged items such as snack foods. For example, a vertical-type form-fill-seal machine known as a pillow packaging machine uses a former and a tube to form a packaging material, which is a sheet of film, into a cylindrical shape; uses a vertical seal mechanism to thermally fuse a vertical edge of the overlapped packaging material; and forms a tubular packaging material. This form-fill-seal machine also fills an interior of the tubular packaging material with a packaged item through a tube, and uses a lateral seal mechanism under the tube to thermally fuse across an upper end part of the bag and a lower end part of a subsequent bag.
Form-fill-seal machines of such description also include those that perform bag manufacture while forming a gusset (i.e., an inwardly-folded portion) at positions corresponding to both side parts of the bag. For example, a vertical-type form-fill-seal machine disclosed in patent literature 1 (JP-A 7-156908) drives so as to insert/remove a pair of left and right gusset plates against an intermittently conveyed packaging material, and is thereby capable of forming a gusset on a side part of a bag.